Class 9 CBSE Science — Chapter 12: Earth as a System: Energy, Matter & Life MCQs with Answers
90 practice questions · 30 Easy · 30 Medium · 30 Hard
Practise the most important Class 9 CBSE Science questions from Chapter 12, "Earth as a System: Energy, Matter & Life" — 9 separately timed quizzes built from 90 NCERT-aligned multiple-choice questions, with answers and explanations. The set is split into 30 Easy, 30 Medium and 30 Hard, so you can warm up on the fundamentals and then push into the exam-level problems that separate top scorers in CBSE Board exams and the JEE & NEET foundation years.
"Earth as a System: Energy, Matter & Life" is one of the chapters where concept clarity across physics, chemistry and biology basics really pays off. Each MCQ on this chapter is timed and uses exam-grade marking (+4 correct, −1 wrong, 0 skipped), training the accuracy-under-pressure that real papers demand. Every question carries a short explanation, so a wrong answer becomes a quick lesson rather than a dead end — the fastest way to close gaps before a test.
Use this chapter as targeted revision: attempt the Easy set first to confirm your basics on Earth as a System: Energy, Matter & Life, then move to Medium and Hard to test application and problem-solving. Your accuracy, streaks and XP save automatically, and the chapter feeds into your overall Class 9 Science mastery score. 14 sample questions are solved in full below — answer and worked explanation — and signing in free opens all 90.
Key concepts: Earth as a System: Energy, Matter & Life (Class 9 Science)
The Earth works as a single system of interacting spheres — geosphere, hydrosphere, atmosphere, cryosphere and biosphere — driven by energy from the Sun. Uneven heating drives winds and currents, matter is recycled through biogeochemical cycles, and human activity is now altering both.
- Earth as a system
- The Earth's components are not independent: a change in one sphere produces changes in the others, so the planet behaves as a single interacting system.
- Geosphere
- The solid Earth — crust, mantle and core — which supplies mineral nutrients and forms the land surface on which life depends.
- Hydrosphere
- All the water on Earth: oceans, rivers, lakes and groundwater. Water's high heat capacity makes it a powerful moderator of temperature.
- Atmosphere
- The envelope of gases around the Earth, roughly 78% nitrogen and 21% oxygen, which shields life from harmful radiation and holds in heat.
Class 9 Science Earth as a System: Energy, Matter & Life MCQs with answers
14 solved questions across the difficulty levels this chapter is graded on — answer and explanation shown for each. The remaining 76 are timed and scored when you sign in.
- Q1Easy
The primary source of energy for almost all processes on the Earth is the:
A.WindB.MoonC.Sun✓ CorrectD.OceanAnswer: C. Sun
Explanation: The Sun powers nearly every Earth process — weather, the water cycle, photosynthesis — by radiating energy across space; wind and ocean currents only redistribute heat the Sun already supplied.
- Q2Easy
All the water on the Earth — oceans, rivers, lakes and groundwater — makes up the:
A.AtmosphereB.BiosphereC.GeosphereD.Hydrosphere✓ CorrectAnswer: D. Hydrosphere
Explanation: The hydrosphere is the Earth's water sphere — oceans, rivers, lakes and groundwater together — distinct from the biosphere (living things), geosphere (rock and soil) and atmosphere (gases).
- Q3Easy
All the living organisms on the Earth together form the:
A.CryosphereB.Biosphere✓ CorrectC.AtmosphereD.GeosphereAnswer: B. Biosphere
Explanation: The biosphere is the zone where all living organisms exist and interact; it differs from the cryosphere (frozen water), atmosphere (gases) and geosphere (rock and soil).
- Q4Easy
The blanket of gases surrounding the Earth is called the:
A.Atmosphere✓ CorrectB.GeosphereC.BiosphereD.HydrosphereAnswer: A. Atmosphere
Explanation: The atmosphere is the layer of gases held around the Earth by gravity, distinct from the geosphere (rock), biosphere (life) and hydrosphere (water).
- Q5Easy
The frozen-water part of the Earth — ice caps, glaciers and snow — is called the:
A.AtmosphereB.HydrosphereC.GeosphereD.Cryosphere✓ CorrectAnswer: D. Cryosphere
Explanation: The cryosphere covers all frozen water on Earth — ice caps, glaciers and snow — as opposed to liquid water in the hydrosphere or the gaseous atmosphere.
- Q6Easy
The solid part of the Earth, made of rocks and soil, is called the:
A.BiosphereB.HydrosphereC.Geosphere✓ CorrectD.AtmosphereAnswer: C. Geosphere
Explanation: The geosphere (lithosphere) is Earth's solid rocky and soil layer, distinct from the biosphere (life), hydrosphere (water) and atmosphere (gases).
- Q7Medium
The equator receives more heat than the poles because there the Sun's rays fall:
A.More slantingB.Only at nightC.NeverD.More directly (vertically)✓ CorrectAnswer: D. More directly (vertically)
Explanation: The equator receives more heat because sunlight strikes it almost vertically, concentrating energy on a small area, while polar rays hit at a slant and spread out over a wider one.
- Q8Medium
Nitrogen-fixing bacteria are important because they convert atmospheric nitrogen into:
A.OxygenB.WaterC.Nitrogen compounds usable by plants✓ CorrectD.Carbon dioxideAnswer: C. Nitrogen compounds usable by plants
Explanation: Nitrogen-fixing bacteria convert inert atmospheric N₂ into nitrogen compounds like ammonia and nitrates that plants can actually absorb and use to build proteins.
- Q9Medium
Rhizobium, a nitrogen-fixing bacterium, lives in the root nodules of:
A.MossesB.GrassesC.CactiD.Leguminous plants (like beans and peas)✓ CorrectAnswer: D. Leguminous plants (like beans and peas)
Explanation: Rhizobium bacteria live symbiotically in the root nodules of leguminous plants like beans and peas, fixing nitrogen in exchange for nutrients from the host.
- Q10Medium
During a thunderstorm, lightning helps the nitrogen cycle by converting nitrogen gas into:
A.OxygenB.Oxides of nitrogen (which form nitrates)✓ CorrectC.Carbon dioxideD.Ammonia gas onlyAnswer: B. Oxides of nitrogen (which form nitrates)
Explanation: The intense energy of lightning fuses atmospheric nitrogen and oxygen into nitrogen oxides, which dissolve in rain to form nitrates that enrich the soil.
- Q11Medium
In the carbon cycle, carbon dioxide is returned to the atmosphere mainly by:
A.PhotosynthesisB.EvaporationC.Respiration and combustion✓ CorrectD.CondensationAnswer: C. Respiration and combustion
Explanation: In the carbon cycle, respiration by living things and combustion of fuels release carbon dioxide back into the atmosphere, balancing the CO₂ that photosynthesis removes.
- Q12Hard
Why is the equator much warmer than the poles?
A.The equator is closer to the Sun than the polesB.At the equator sunlight falls almost vertically, while at the poles it is spread over a larger area✓ CorrectC.The poles get no sunlight at allD.The equator has no atmosphereAnswer: B. At the equator sunlight falls almost vertically, while at the poles it is spread over a larger area
Explanation: Because Earth is curved, equatorial sunlight strikes almost vertically onto a small area, while polar sunlight arrives at a slant and spreads over a much larger area — not because the equator is physically closer to the Sun.
- Q13Hard
During the day, a sea breeze blows from sea to land because:
A.Warm air over the land rises and cooler air from the sea moves in to take its place✓ CorrectB.The sea is hotter than the landC.The land is colder than the seaD.There is no sunlight during the dayAnswer: A. Warm air over the land rises and cooler air from the sea moves in to take its place
Explanation: The land heats up faster than the sea, so air above it warms and rises, and cooler, denser sea air rushes in to take its place — this inflow is the sea breeze, not a case of the sea being hotter.
- Q14Hard
At night, a land breeze blows from land to sea because:
A.The land stays warmer than the seaB.The sea freezes at nightC.Winds always blow towards the seaD.The land cools faster than the sea, so air rises over the warmer sea and land air moves out✓ CorrectAnswer: D. The land cools faster than the sea, so air rises over the warmer sea and land air moves out
Explanation: At night the land cools faster than the sea, so air rises over the relatively warmer sea, and cooler land air flows out to replace it — the land breeze, not the land staying warmer.
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Start this chapter free →Earth as a System: Energy, Matter & Life — FAQs
What are the key concepts in Class 9 Science Earth as a System: Energy, Matter & Life?+
The Earth works as a single system of interacting spheres — geosphere, hydrosphere, atmosphere, cryosphere and biosphere — driven by energy from the Sun. Uneven heating drives winds and currents, matter is recycled through biogeochemical cycles, and human activity is now altering both. Key ideas include Earth as a system, Geosphere, Hydrosphere, Atmosphere.
What does Class 9 Science Chapter 12 (Earth as a System: Energy, Matter & Life) cover on XamBaaz?+
It covers 90 NCERT-aligned MCQs on "Earth as a System: Energy, Matter & Life" — 30 Easy, 30 Medium and 30 Hard — making 9 separately timed quizzes you can sit without ever repeating the same set, each with an instant explanation, suitable for CBSE Board exams and the JEE & NEET foundation years.
Are these "Earth as a System: Energy, Matter & Life" questions free to practise?+
Yes — sign in with Google to practise "Earth as a System: Energy, Matter & Life" free. Full unlimited access is ₹999/year (limited-time launch price), with no per-chapter charges.
How should I revise "Earth as a System: Energy, Matter & Life" for the exam?+
Start with the Easy quiz to confirm your fundamentals, then attempt Medium and Hard for application-level practice. There are 9 separately timed quizzes on this chapter, so you can come back and get a fresh set rather than re-sitting one you have seen. Review each explanation, retry the questions you miss, and track your accuracy on this chapter until it is consistently high.
Are these "Earth as a System: Energy, Matter & Life" MCQs available with answers?+
Yes. 14 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to practise all 90 questions with instant scoring.
Is there negative marking in the "Earth as a System: Energy, Matter & Life" quizzes?+
Yes — the timed quizzes use exam-grade marking: +4 for a correct answer, −1 for a wrong one and 0 for a skipped question. Note that MHT-CET and the CBSE board papers themselves carry no negative marking — our mocks for those are scored their way, not this way.
Are these important questions for Earth as a System: Energy, Matter & Life?+
The set is curated to the NCERT syllabus and weighted toward the question patterns that actually appear in CBSE Board exams and the JEE & NEET foundation years, across Easy, Medium and Hard — so it doubles as an "important questions" revision list for "Earth as a System: Energy, Matter & Life".